Follow-up question for Stack READMEs... the explanatory text on the stack's README tab says:

README templates can reference Stack outputs and resource properties.

Is there special syntax for referencing resource properties? All the examples I can find refer to outputs only.

That would be a mistake in our docs. Currently there is not a way to directly reference resource outputs. However, you can export a resource as an output on your stack or export specific properties of a resource as a stack output

Gotcha; thanks for the clarification 👍